An elated Reggie Warren has finally realized his dream and has made it into space on a routine mission of a construction EVA and scientific reasearch. All does not go well for long, however, turning his dream into a nightmare. While Reggie and Japanese astronaut Hiro Furukawa are outside the orbiter on an extended EVA there is an accidental release of mercury sulphur gas during one of the experiments inside of the shuttle. On their return inside they find the 2 scientists disoriented, sweating and confused as to what has happened. Reggie must muster all of his faculties to return the Shuttle back to earth and save himself and his crew as he realizes that he too has been exposed to the toxic gas.